Yes, I think the government should use every tool at its disposal to combat foreign interference. Expelling a single diplomat is pointless. That's not how you tackle the overall issue of foreign interference.
I think there's a whole range of tools that the government needs to use. If we look at other democratic allies, we see that they've been much more willing to expel diplomats of authoritarian states when those diplomats are engaged in activities that are inconsistent with their diplomatic or consular status.
I think recently of the fact that Germany expelled some 20 Russian diplomats, just in the last several weeks, for activities that were subversive.